The historical establishment of Fuzhou city (Eastern Min) is quite different from the historical establishment of Quanzhou city (Southern Min) i.e. Quanzhou language didn't split off from Fuzhou language.

I somewhat (but not entirely) agree with the author of the link below. If we base languages on mutual intelligibility, there are at least a few thousand Chinese languages in China and not just 7 in the 'standard' classification.